>>12036
>Where he got that info?
It's not just his info.
Lots of contemporary descriptions of battles depicts the closing accord of a battle that way. From the top of my head: Battle of Clontarf (or how it is written), the fleeing vikings were drowned into the sea. But for me it's quite natural knowledge. The warfare of the steppe people based on breaking the lines of the enemy, creating chaos and confusion, send them to flee then hunt them down. Hungarian did this to Euros then Mongols did this to Hungarians in - for example - the Battle of Muhi. The Hungarian camp was surrounded with the exception of a small gap and crushed until the soldiers started to flee then their small bands were hunted down at the gap. Of course the main reason for this move was the wish of Batu to capture king Béla but they salughtered anyone they could reach.
And the casualties aren't just dead but wounded and missing (deserters or unknown dead) and Grossman talks about killings. The battlefield produced wounded, maimed and dying very efficiently, less "right at that moment" dead.